I've been reading lots of messages/posts/articles on cable
directionality lately, and I thought I'd share my insights.

IMO, directionality is real, and is related to grain boundaries.
I race electric R/C cars. We use multi-strand 14 or 12 AWG wire, for
the most part. Our motors pull about 35 A on average, with spikes of
.... 500 amps or more.
One area where I think directionality plays, is the brushes. These are
sintered blocks of copper/silver/graphite, quite grainy.
Out of the package, all brushes are identical. Run them once , and they
act directional. they build up resistance in the direction that they
are used. Reverse them, and they make more power. For a while. You
can't keep alternating though, once you've used them in both
directions, they're basically 'used'.
Another area where I think directionality is in play is the cables of a
welder. Well ,the cables + connectors. They too build up resistance,
gradually. Reverse them, and they're like new.

I think A) extreme currents and B) grain boundaries are essential
ingredients to the appearance of directionality. I would even say grain
boundaries act as little diodes.

So, my response to all those posts/articles saying "I have tested
such-and-such in my lab, and I didn't measure any directionality, so it
doesn't exist and it's an urban myth", is: look closer.
You can't say "I tested this and found nothing, so it doesn't exist".
"It wasn't in my physics handbook, so it isn't true".
You could say something like "I have tested in x different conditions
which I think are representative, so the probability that it doesn't
exist in my cables under my circumstances is very high."
There are a million thing that we don't know yet. I still don't know
what happens when 500 amps run though a 16 AWG wire.
I say: step up the current and you'll find things you haven't seen
before.

wrote:
snip
There are a million thing that we don't know yet. I still don't know
what happens when 500 amps run though a 16 AWG wire.
I say: step up the current and you'll find things you haven't seen
before.

Likely it becomes vaporized?

But your anecdotes on welding cable and R/C race cars are interesting.
It would be nice to see some scientifically derived measurements of
these effects and the elimination of other "confounding" factors from
the "effects".

But, please keep in mind that the signal in audio is AC not DC, so even
if there is a DC effect, it would not seem to be present in AC
conditions! :- )

_-_-bear

wrote:
I've been reading lots of messages/posts/articles on cable
directionality lately, and I thought I'd share my insights.

IMO, directionality is real, and is related to grain boundaries.
I race electric R/C cars. We use multi-strand 14 or 12 AWG wire, for
the most part. Our motors pull about 35 A on average, with spikes of
... 500 amps or more.
One area where I think directionality plays, is the brushes. These are
sintered blocks of copper/silver/graphite, quite grainy.
Out of the package, all brushes are identical. Run them once , and they
act directional. they build up resistance in the direction that they
are used. Reverse them, and they make more power. For a while. You
can't keep alternating though, once you've used them in both
directions, they're basically 'used'.
Another area where I think directionality is in play is the cables of a
welder. Well ,the cables + connectors. They too build up resistance,
gradually. Reverse them, and they're like new.

I think A) extreme currents and B) grain boundaries are essential
ingredients to the appearance of directionality. I would even say grain
boundaries act as little diodes.

So, my response to all those posts/articles saying "I have tested
such-and-such in my lab, and I didn't measure any directionality, so it
doesn't exist and it's an urban myth", is: look closer.
You can't say "I tested this and found nothing, so it doesn't exist".
"It wasn't in my physics handbook, so it isn't true".
You could say something like "I have tested in x different conditions
which I think are representative, so the probability that it doesn't
exist in my cables under my circumstances is very high."
There are a million thing that we don't know yet.

There are more than a million things that we don't know yet, but one
thing we know how to do is to make very sensitive measurements of
distortion. If there is directionality in cables, then the resistance in
one direction must be different than in the other. It *must* show up in
distortion measurements.


I still don't know
what happens when 500 amps run though a 16 AWG wire.

Do you know that there is a heating effect, and that the power
dissipated is proportinal to the product of the square of the current
and the resistance of the wire?

I say: step up the current and you'll find things you haven't seen
before.

The fact that you have not seen it before does not mean that it is not
explained in sufficient detail by science as we know today.

chung wrote:
If there is directionality in cables, then the resistance in
one direction must be different than in the other. It *must* show up in
distortion measurements.

....or in resistance measurements, eh?